/*
 * Copyright (c) 2018-2022, Andreas Kling <andreas@ladybird.org>
 * Copyright (c) 2025, Jelle Raaijmakers <jelle@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibUnicode/CharacterTypes.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/TextPrototype.h>
#include <LibWeb/DOM/Range.h>
#include <LibWeb/DOM/Text.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/HTML/Window.h>
#include <LibWeb/Layout/TextNode.h>

namespace Web::DOM {

GC_DEFINE_ALLOCATOR(Text);

Text::Text(Document& document, Utf16String data)
    : CharacterData(document, NodeType::TEXT_NODE, move(data))
{
}

Text::Text(Document& document, NodeType type, Utf16String data)
    : CharacterData(document, type, move(data))
{
}

void Text::initialize(JS::Realm& realm)
{
    WEB_SET_PROTOTYPE_FOR_INTERFACE(Text);
    Base::initialize(realm);
}

void Text::visit_edges(Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    SlottableMixin::visit_edges(visitor);
}

// https://dom.spec.whatwg.org/#dom-text-text
WebIDL::ExceptionOr<GC::Ref<Text>> Text::construct_impl(JS::Realm& realm, Utf16String data)
{
    // The new Text(data) constructor steps are to set this’s data to data and this’s node document to current global object’s associated Document.
    auto& window = as<HTML::Window>(HTML::current_principal_global_object());
    return realm.create<Text>(window.associated_document(), move(data));
}

// https://dom.spec.whatwg.org/#dom-text-splittext
// https://dom.spec.whatwg.org/#concept-text-split
WebIDL::ExceptionOr<GC::Ref<Text>> Text::split_text(size_t offset)
{
    // 1. Let length be node’s length.
    auto length = this->length();

    // 2. If offset is greater than length, then throw an "IndexSizeError" DOMException.
    if (offset > length)
        return WebIDL::IndexSizeError::create(realm(), "Split offset is greater than length"_utf16);

    // 3. Let count be length minus offset.
    auto count = length - offset;

    // 4. Let new data be the result of substringing data with node node, offset offset, and count count.
    auto new_data = TRY(substring_data(offset, count));

    // 5. Let new node be a new Text node, with the same node document as node. Set new node’s data to new data.
    auto new_node = realm().create<Text>(document(), new_data);

    // 6. Let parent be node’s parent.
    GC::Ptr<Node> parent = this->parent();

    // 7. If parent is not null, then:
    if (parent) {
        // 1. Insert new node into parent before node’s next sibling.
        parent->insert_before(*new_node, next_sibling());

        // 2. For each live range whose start node is node and start offset is greater than offset, set its start node
        //    to new node and decrease its start offset by offset.
        for (auto* range : Range::live_ranges()) {
            if (range->start_container() == this && range->start_offset() > offset) {
                range->set_start_node(*new_node);
                range->decrease_start_offset(offset);
            }
        }

        // 3. For each live range whose end node is node and end offset is greater than offset, set its end node to new
        //    node and decrease its end offset by offset.
        for (auto* range : Range::live_ranges()) {
            if (range->end_container() == this && range->end_offset() > offset) {
                range->set_end_node(*new_node);
                range->decrease_end_offset(offset);
            }
        }

        // 4. For each live range whose start node is parent and start offset is equal to the index of node plus 1,
        //    increase its start offset by 1.
        for (auto* range : Range::live_ranges()) {
            if (range->start_container() == parent.ptr() && range->start_offset() == index() + 1)
                range->increase_start_offset(1);
        }

        // 5. For each live range whose end node is parent and end offset is equal to the index of node plus 1, increase
        //    its end offset by 1.
        for (auto* range : Range::live_ranges()) {
            if (range->end_container() == parent.ptr() && range->end_offset() == index() + 1)
                range->increase_end_offset(1);
        }
    }

    // 8. Replace data with node node, offset offset, count count, and data the empty string.
    TRY(replace_data(offset, count, {}));

    // 9. Return new node.
    return new_node;
}

// https://dom.spec.whatwg.org/#dom-text-wholetext
Utf16String Text::whole_text()
{
    // https://dom.spec.whatwg.org/#contiguous-text-nodes
    // The contiguous Text nodes of a node node are node, node’s previous sibling Text node, if any, and its contiguous
    // Text nodes, and node’s next sibling Text node, if any, and its contiguous Text nodes, avoiding any duplicates.
    Vector<Text*> nodes;

    nodes.append(this);

    auto* current_node = previous_sibling();
    while (current_node && (current_node->is_text() || current_node->is_cdata_section())) {
        nodes.append(static_cast<Text*>(current_node));
        current_node = current_node->previous_sibling();
    }

    // Reverse nodes so they are in tree order
    nodes.reverse();

    current_node = next_sibling();
    while (current_node && (current_node->is_text() || current_node->is_cdata_section())) {
        nodes.append(static_cast<Text*>(current_node));
        current_node = current_node->next_sibling();
    }

    StringBuilder builder(StringBuilder::Mode::UTF16);
    for (auto const& text_node : nodes)
        builder.append(text_node->data());

    return builder.to_utf16_string();
}

// https://html.spec.whatwg.org/multipage/dom.html#text-node-directionality
Optional<Element::Directionality> Text::directionality() const
{
    // 1. If text's data does not contain a code point whose bidirectional character type is L, AL, or R, then return null.
    // 2. Let codePoint be the first code point in text's data whose bidirectional character type is L, AL, or R.
    Optional<Unicode::BidiClass> found_character_bidi_class;
    for (auto code_point : data()) {
        auto bidi_class = Unicode::bidirectional_class(code_point);
        if (first_is_one_of(bidi_class, Unicode::BidiClass::LeftToRight, Unicode::BidiClass::RightToLeftArabic, Unicode::BidiClass::RightToLeft)) {
            found_character_bidi_class = bidi_class;
            break;
        }
    }
    if (!found_character_bidi_class.has_value())
        return {};

    // 3. If codePoint is of bidirectional character type AL or R, then return 'rtl'.
    if (first_is_one_of(*found_character_bidi_class, Unicode::BidiClass::RightToLeftArabic, Unicode::BidiClass::RightToLeft))
        return Element::Directionality::Rtl;

    // 4. If codePoint is of bidirectional character type L, then return 'ltr'.
    // NOTE: codePoint should always be of bidirectional character type L by this point, so we can just return 'ltr' here.
    VERIFY(*found_character_bidi_class == Unicode::BidiClass::LeftToRight);
    return Element::Directionality::Ltr;
}

}
